[llvm] [VPlan] Fix nowrap flags for strided access pointers from SCEV (PR #209453)

[Florian Hahn via llvm-commits]

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@@ -7785,18 +7785,17 @@ void VPlanTransforms::convertToStridedAccesses(VPlan &Plan,
           VectorLoop->getCanonicalIV(), IndexTy,
           VectorLoop->getCanonicalIVType(), DebugLoc::getUnknown());
       auto *AddRecPtr = cast<SCEVAddRecExpr>(PtrSCEV);
-      auto *Offset = Builder.createOverflowingOp(
-          Instruction::Mul, {CanIV, StrideInBytes},
-          {AddRecPtr->hasNoUnsignedWrap(), AddRecPtr->hasNoSignedWrap()});
-      auto *BasePtr = Builder.createNoWrapPtrAdd(
-          StartVPV, Offset,
-          AddRecPtr->hasNoUnsignedWrap() ? GEPNoWrapFlags::noUnsignedWrap()
-                                         : GEPNoWrapFlags::none());
+      auto *Offset =
+          Builder.createOverflowingOp(Instruction::Mul, {CanIV, StrideInBytes});
+      GEPNoWrapFlags NWFlags = AddRecPtr->hasNoUnsignedWrap()
+                                   ? GEPNoWrapFlags::noUnsignedWrap()
+                                   : GEPNoWrapFlags::none();
+      auto *BasePtr = Builder.createNoWrapPtrAdd(StartVPV, Offset, NWFlags);
 
       // Create a new vector pointer for strided access.
       VPValue *NewPtr = Builder.createVectorPointer(
-          BasePtr, Type::getInt8Ty(Plan.getContext()), StrideInBytes,
-          Ptr->getGEPNoWrapFlags(), Ptr->getDebugLoc());
+          BasePtr, Type::getInt8Ty(Plan.getContext()), StrideInBytes, NWFlags,
+          Ptr->getDebugLoc());
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fhahn wrote:

I think for a test where `nsw` would need to be dropped we would need a loop with unknown trip count and unknown start of the second IV.

https://github.com/llvm/llvm-project/pull/209453